Geothermal energy refers to heat, also called ‘thermal,’ that is extracted from the earth, or ‘geo.’ This heat is harnessed and used to generate electricity. Depending on the geophysical conditions that exist in a particular area, different technologies can be used to utilize this energy.

Geothermal energy is not a new concept. Ancient civilization used geothermal energy for heating, medicinal purposes, bathing and cooking. Today, geothermal energy is used for heating, aquaculture and to generate electricity.

How it works

To access the geothermal energy, a well must be dug deep in the earth to tap into a pool of geothermally heated water. Several methods can be used for extracting this hot water, including binary-cycle, flash steam or dry steam power plant. 

Binary-cycle – This method passes the geothermal water through a heat exchanger, which heats a secondary fluid. This secondary fluid vaporizes at a lower temperature than the water and this vapor spins a turbine/electricity generator. The fluid is then condensed back to a liquid and re-vaporized, thus continuing the process.

Flash steam – This method involves bringing the high-pressure geothermal water to the earth’s surface. During the trip to the surface, the water pressure is naturally decreased, causing some of the water to flash into steam. This steam then turns the blade of a turbine, which then generates electricity.

Dry steam – This method involves mostly steam and very little water. The steam is extracted directly sent to the turbine.

The benefits of geothermal

Geothermal is a clean resource that requires no fuel and produces no emissions. In addition, it’s a continuous source of reliable energy that is sustainable and reusable. Geothermal water can be recycled and reused. Geothermal power plants do not require a lot of land and can be easily integrated into the local area with minimal impact. Lastly, geothermal plants are flexible and modular in nature, meaning they can be installed incrementally as needed to meet growing electricity demands.

Arizona has several sites across the state where there is strong potential for geothermal energy. Several groups are researching this potential.

For more information about Geothermal energy please follow these links:

APS Geothermal Energy Presentation

http://www.aps.com/images/PDF/renewable/GeothermalEnergyPresentation.pdf

APS Geothermal Energy Poster

http://www.aps.com/images/PDF/renewable/GeothermalEnergyGraphic.pdf

SRP Geothermal Energy Links

http://www.srpnet.com/environment/renewable.aspx#geo